CSR Blog: Fighting Fire with Fire in the South China Sea: The Case for Strengthening the Gray Zone Capabilities of Vietnam to Counter Chinese Gray Zone Tactics

By Samuel Olson

Territorial disputes in the South China Sea have emerged as one of the most pressing issues in East and Southeast Asia. China claims sovereignty over everything within the so-called “nine-dash line” in the South China Sea, parts of which are concurrently claimed by Malaysia, Vietnam, Indonesia, Brunei, the Philippines, and Taiwan. To enforce its sovereignty, China has deployed coast guard, maritime militia, as well as research vessels and oil rigs to disputed maritime areas to assert sovereignty, a phenomenon which analysts have termed “gray zone tactics.”1 The use of gray zone tactics by China in the South China Sea has not abated, with its most recent deployment of  maritime militia vessels to occupy the Philippine’s Whitsun Reef. In response to China’s gray zone maneuvering, multiple claimant countries have voiced opposition, with Vietnam emerging as one of China’s greatest critics.2 

While the majority of analysis and attention has been focused on China, it is not the only claimant country that employs gray zone tactics in the South China Sea – Vietnam also uses a similar approach to defend its maritime sovereignty at the lowest possible cost.3 The difference, however, is that China’s regional military superiority gives it the freedom to choose between gray zone tactics or military force. In contrast, with its smaller, less capable military, Vietnam can only realistically employ gray zone tactics to respond to Chinese encroachments on its sovereignty. While it is possible for the United States to intervene militarily in the South China Sea, it is unlikely the U.S. would defend Vietnam given Vietnam’s “Three No’s” defense strategy, which includes “no reliance on any country to combat others.”

Recently, the Biden administration has aimed to re-energize relationships with U.S. allies and partners – Vietnam being named as one of the most important partners in Southeast Asia.4 The new administration has also made it a priority to combat China’s aggressive actions in the South China Sea. Given Vietnam’s limited options, the United States’ approach to countering Chinese gray zone tactics in the South China Sea should incorporate continued support for Vietnam’s ability to operate in the gray zone. 

In this article, I will first briefly discuss gray zone tactics and how asymmetry influences the degree of freedom countries have in choosing to deploy them. Then, I will examine how China and Vietnam use gray zone tactics to assert their sovereignty in the South China Sea. Finally, I will conclude with a discussion on the implications of Vietnam’s use of gray zone actions in informing America’s response to Chinese actions in the South China Sea. 

Asymmetry and the Use of Gray Zone Tactics 

Gray zone tactics are defined as, “an effort or series of efforts beyond steady-state deterrence and assurance that attempt to achieve one’s security objectives without resorting to direct and sizable use of force.” Gray zone tactics are often characterized by descriptive and normative ambiguity. Descriptive ambiguity attempts to control information and create doubt over what action actually occurred.5 For example, Vietnam characterized itself as the “victim” in domestic and international media after deploying its coast guard vessels to disrupt Chinese oil rig  HYS-981’s operations in Vietnam’s exclusive economic zone (EEZ). Normative ambiguity attempts to create confusion over legal violations. For example, China’s deployment of maritime militia vessels to the Philippine’s EEZ raises questions of whether or not international norms have been violated. By employing ambiguity, the likelihood of the opponent choosing to respond with armed conflict decreases. 

While the drivers of gray zone tactics are complex, asymmetries in capabilities and relative importance influence the options a country has to assert its sovereignty claims. Among the South China Sea claimant countries, China by far possesses the greatest military capability and economic clout. Such asymmetry supplies China with the freedom to deploy either military or nonmilitary forces. Although it can easily coerce other countries with its greater military capabilities, deploying them directly runs the risk of an aggressive response from the United States, raising the risk of armed conflict.6 For example, although the United States is not a South China Sea claimant country, it signed a Mutual Defense Treaty with the Philippines in 1951, which requires the United States to come to Manila’s defense in the event that Manila’s personnel, assets, or vessels are attacked in the Pacific. Furthermore, choosing to deploy non-military assets like the coast guard and maritime militia allows China to enforce its sovereignty claims while lowering the possibility of an intense armed response, and thereby allowing it to pursue its political objectives at a lower overall cost.7     

Vietnam, however, as the weaker country, is forced to rely on gray zone tactics to defend its sovereignty claims. First, Vietnam’s military is considerably smaller than China’s, meaning that it would most certainly lose in a conflict with China.8 Although Vietnam has attempted to modernize its military in order to deter Chinese actions in the South China Sea, a military response may still be viewed as overly aggressive by China.9 In addition, the dependence of Vietnam’s economy on Chinese trade and investment means provoking an armed conflict with China would also carry negative economic consequences.10 

Although China and Vietnam both resort to gray zone tactics to avoid conflict, the stakes are much higher for Vietnam. China’s military is rapidly gaining parity with and even overtaking the United States in domains such as fleet size and conventional ballistic and cruise missiles. Thus, the shrinking gap between Chinese and American military capability means that while China would prefer to avoid conflict, a war with America would not be as costly to China as conflict with China would be to Vietnam, a country which will likely never reach or surpass China’s military capabilities. Therefore, Vietnam’s less capable military and economic dependence on China means it cannot realistically afford to employ a more provocative option like military force to enforce its sovereignty. Given these realities, Vietnam is essentially forced to use gray zone tactics to assert its sovereignty and avoid triggering an armed conflict. 

China’s Use of Gray Zone Tactics in the South China Sea 

Among the South China Sea claimant countries, China is the most frequent employer of gray zone tactics. The most prominent prongs of China’s approach in the South China Sea are the  China Coast Guard (CCG) and People’s Armed Forces Maritime Militia (PAFMM). The CCG is the largest coast guard in the world and is often used to assert Chinese sovereignty claims and harass other claimants.11  For example, China has regularly dispatched CCG vessels to ram Vietnamese fishing vessels near the Paracel Islands, escort Chinese fishing vessels in Indonesia’s EEZ and research vessels in Vietnam’s EEZ, and hamper oil drilling operations in Malaysian waters.

China’s other gray zone prong, the maritime militia, is also commonly used to enforce Chinese maritime sovereignty claims because it provides plausible deniability over the use of force.12 The PAFMM provides plausible deniability to Chinese sovereignty assertion by allowing China to claim that the fishing vessels operating in disputed waters are merely civilians acting independently of government control. Despite evidence to the contrary and numerous reports in Chinese media, the Chinese government still denies the PAFMM’s role in sovereignty enforcement. Although downplayed publicly by the Chinese government, the maritime militia has been identified as playing the primary role in enforcing Chinese maritime sovereignty in the South China Sea.13 The PAFMM enforces Chinese fishing bans, conducts illegal fishing activities, assists in land reclamation, denies access to contested areas, and harasses the fishing vessels of other claimant countries.14

Vietnam’s Use of Gray Zone Tactics in the South China Sea 

Vietnam has also resorted to gray zone approaches that are remarkably similar to China’s actions, such as using coast guard and maritime militia to defend its maritime sovereignty claims. The most prominent example is Vietnam’s response to the HYSY-981 oil rig incident. In 2014, Vietnam discovered China National Offshore Oil Corporation’s (CNOOC) HYSY-981 oil rig and three escort vessels operating roughly 17 nautical miles south off of Triton Island in the Paracel Islands.15 Triton Island, also known as Zhongjian Dao (中建岛/中建島) or Đảo Tri Tôn, is a disputed territory concurrently claimed by China, Taiwan, and Vietnam.  In response, Vietnam deployed the Fisheries Resources Surveillance and Vietnam Coast Guard vessels to the HYSY-981 oil rig to prevent it from establishing a fixed position, demanding the rig’s removal. In addition, Vietnam deployed its own maritime militia to interfere with HYSY-981’s operations. For example, on May 10th, Truong Tan Sang, then President of Vietnam, in conjunction with the Vietnam Fisheries Society, encouraged Vietnamese fishing vessels to travel to the area where HYSY-981 was stationed.

The HYSY-981 incident is only one of many examples of Vietnamese use of gray zone tactics. In 2006 and 2007, Vietnamese coast guard ships harassed a Chinese seismic research vessel near the Paracel Islands. Three years later in 2010, Vietnamese fishing boats harassed Chinese fishing vessels near the Spratly Islands.16 In 2011, Vietnam dispatched ships to interfere with a Chinese research ship near Triton Island.17 Most recently, in 2019, Vietnam sent both its coast guard and maritime militia to disrupt Chinese research vessel Haiyang Dizhi 8 from operating in Vanguard Bank and extended the operation of a Japanese-owned oil rig in the disputed area.

Implications for the United States’ Approach to Countering Chinese Gray Zone Tactics

U.S. foreign policy in the South China Sea needs to be based on the complicated security concerns of the different state actors in the region. It is apparent that China is not the only gray zone actor in the South China Sea: Vietnam also has a demonstrated history of deploying its coast guard and maritime militia to defend its maritime sovereignty claims. However, unlike China, Vietnam has little choice but to use gray zone tactics. Understanding this fact is vital to informing U.S. policy. 

The Biden administration has already taken steps to counter China’s gray zone tactics: Army General Richard Clark recently announced the formation of a Special Operations Task Force focused on combating Chinese disinformation – a classic gray zone tool that China has used to influence international perceptions of its sovereignty claims in the South China Sea.18 Vietnam has presented itself as a key partner for standing up to China in the South China Sea based on its frequent vocal opposition of Chinese actions.19 Indeed, in recent years, the U.S. has signaled through numerous trips by government officials to Vietnam that it views the country as a strategic partner.20 In response, Vietnam has tacitly signaled support for the U.S. Indo-Pacific Strategy.21  

To effectively support Vietnam’s ability to resist Chinese gray zone tactics, the United States should provide assistance that will best match Vietnam’s capabilities and approach to China.   Despite loosened restrictions on weapons sales, Vietnam has held off on major arms purchases from the U.S. to avoid appearing too provocative to China.22 Therefore, it is unlikely the U.S. can rely on the sale of conventional military weapons to help Vietnam counter China in the South China Sea. Instead, the United States should focus on strengthening Vietnam’s ability to operate under the threshold of armed conflict. Previous administrations have provided ships and additional support to the Vietnam Coast Guard. Since the Obama administration announced the Indo-Pacific Maritime Security Initiative in May 2015, the U.S. has provided the Vietnamese Coast Guard with 24 Metal Shark patrol boats and two cutters. Beyond the sale of ships, the United States has recently completed the construction of a coast guard training center in Vietnam’s Coast Guard Region 3.

Given ongoing Chinese provocation in the South China Sea, the Biden administration should continue strengthening Vietnam as a strategic partner and support its ability to operate in the gray zone. This effort will improve Vietnam’s current capabilities to counter China and enable Vietnam to defend its interests without disturbing the delicate Sino-Vietnamese relationship. If the Biden administration wants to deter Chinese aggression in the South China Sea, it must prioritize U.S. assistance to Vietnam and sustain the precedent set by previous administrations.   

Sam Olson is a 2020 M.A.in International Studies graduate from the Hopkins-Nanjing Center, where he pursued a dual concentration in International Politics and China Studies. Currently based in the Boston area, Sam’s research interests include the South China Sea, Chinese military modernization, Chinese foreign policy in Southeast Asia, and Chinese influence operations, particularly in Central and Eastern Europe. Sam can be reached at samuel.allan.olson@gmail.com.


1 Michael J. Mazarr, Mastering the Gray Zone: Understanding a Changing Era of Conflict ( Carlisle: U.S. Army War College Press, 2015), 83.

2 Tom Fawthrope,“Vietnam mass protests expose Hanoi’s China dilemma,” The Diplomat, June 21, 2018. https://thediplomat.com/2018/06/vietnam-mass-protests-expose-hanois-china-dilemma/.  

3 Kathleen H. Hicks et al., By Other Means Part 1: Campaigning in the Gray Zone (New York: Rowman & Littlefield, 2019), 4; Lyle J. Morris et al.,  Gaining Competitive Advantage in the Gray Zone: Response Options for Coercive Aggression Below the Threshold of War (Santa Monica: RAND Corporation, 2019), 212;  Mazarr, Mastering the Gray Zone, 79; Michael B.Petersen, “The Chinese Maritime Gray Zone: Definitions, Dangers, and the Complications of Rights Protection Operations,” in China’s Maritime Gray Zone Operations, ed.  Andrew S. Erickson and Ryan D. Martinson ( Annapolis: Naval Institute Press, 2019), 11.

4 Derek Grossman,  Regional Responses to U.S.-China Competition in the Indo Pacific: Vietnam (Santa Monica: RAND Corporation, 2020), 1.

5 Michael Green et al., Countering Coercion in Maritime Asia: The Theory and Practice of Gray Zone  Deterrence (New York: Rowman and Littlefield, 2017), 32.

6 Petersen,”The Chinese Maritime Gray Zone: Definitions, Dangers, and the Complications of Rights Protection Operations,” 20. 

7 Petersen, “The Chinese Maritime Gray Zone: Definitions, Dangers, and the Complications of Rights Protection Operations,” 20.

8 Shang-Su Wu, “The Development of Vietnam’s Sea-Denial Strategy,” Naval War College Review 70, no. 1 (2017): 154-55, https://www.jstor.org/stable/26398008/.

9 Grossman, Regional Responses, 14.

10 Frances Yaping Wang  and Brantly Womack,  “Jawing Through Crises: Chinese and Vietnamese Media Strategies in the South China Sea,” Journal of Contemporary China 119, no. 28 (2019): 717.

11 O’Rourke, U.S.- China Strategic Competition in the South and East China Seas: Background and Issues for Congress, 74. 

12 “Maritime Militias in the South China Sea,” Hong Thao Nguyen and Binh Ton-Nu Thanh, The National Bureau of Asian Research, July 13, 2019,  https://www.nbr.org/publication/maritime-militias-in-the-south-china-sea/.

13 O’Rourke, U.S.- China Strategic Competition in the South and East China Seas: Background and Issues for Congress, 75.

14 “Maritime Militias in the South China Sea” ; Ryan Martinson, “Catching Sovereignty Fish: Chinese Fishers in the Southern Spratlys,” Marine Policy 125 (2021): 11.

15 Green et al., Countering Coercion in Maritime Asia, 202,206, 207.

16 Carlyle A. Thayer, “The Tyranny of Geography: Vietnamese Strategies to Constrain China in the South China Sea,” Journal of Contemporary Southeast Asia 33, no. 3 (2011): 359.

17 Green et al., Countering Coercion in Maritime Asia, 204.

18  Hicks et al., By Other Means Part 1, v. 

19 Fawthorpe, “Hanoi’s China Dilemma.

20 Grossman, Regional Responses, 38.

21 Grossman, Regional Responses, 38, 67.

22 Derek Grossman, “U.S. striking just the right balance with Vietnam in South China Sea,”The RAND Blog, November 23, 2017, https://www.rand.org/blog/2017/11/us-striking-just-the-right-balance-with-vietnam-in.html.

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